Automatic device



June 17, 1930. L. CUNNINGHAM 1,765,056

AUTOMATI C DEVICE original Filed Feb. .8, 192e 2 sr ets-sheer 1 4 4 5 al2,4,2029- j 2z -2 i @Q '75% fn ze z /6 I /8 7 n.. l 25 25 2m /6 /77'TOR/vars June 17, 1930. L. L.. CUNNINGHAM 1,765,056

AUTOMAT I C DEVICE Original .Filed Feb. 8, 1,926 2 Sheets-Sheet 2 EY@GMM-m` i7- To RNE Ys Patented June 17, 1930 UNITED STATES PATENT OFFICELEWIS L. CUNNINGHAM, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR, BY MESNEASSIGN- MENTS, TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OFMINNEAPOLIS, MINNESOTA, A CORPORATION OF DELAWARE AUTOMATIC DEVICEApplication led February 8, 1926, Serial No. 86,849. Renewed April 15,1929.

This invention relates to improvements in automatic safety devices andparticularly to a safety device operable by radiant heat or energy, andadaptedfor controlling other devices such as electrical circuits,valves, etc. The invention is an improvement .upon an apparatusdisclosed in a pending application of Lewis L. Cunnin ham for1mprovements in automatic devlces, filed July 24, 1925, Serial No.45,835. To distinguish the present device from the ordinary thermostaticdevices, which would not be effective for applicants preferred use, itis necessary to state 'and to show that these portions of ap licantsdevice through which control is e ected by radiant heat or energy do notrespond to any particular pre-determined temperature, but to differencesin temperature, between the control element, and adjacent controlelement supporting means illustrated in a preferred embodiment hereindescribed.

The broader aspect of function of applicants control device, is promptresponse to the presence or absence of heat or radiant rays, such forexample, as is furnished by a gas, oil or coal flame.

The present invention provides a device in which the proper controlleddeflection of a circuit 'controlling diaphragm is constantly maintainedas long as the diaphragm is receiving a supply of heat. In other words,the proper deflection of the diaphragmatic control element is maintainedin a predetermined degree as long as heatis being received. The deviceis so constructed that it will withstand high temperatures over longperiods. It is further constructed so that a draft cannot passtherethrough, and therefore no deposit 'of carbon upon the diaphragmaticelement in that amount which will prevent proper operation of thediaphragm will take place.

The features of invention include the manner of mounting the controllingelement or diaphragm, with the material of the supporting elements anddiaphragm having the same coefficient of expansion; to the diaphragm perse having its receiving side blackened and its opposite side polished,to

reduce radiation and increase conduction effects; to the construction,of a contact making and vbreaking device operable by and connected withthe diaphragmatic control element; and to the use of a second diaphragmas a heat shield and focusing device for preventing undue heating of thecontrol element.

Other objects and certain advantages will appear from the descriptionofthe drawings forming part of this specification and in said drawings:

'Figure 1 is aside elevation;

Figure 2 is a longitudinally vertical section;

Figure 3 is a cross section on line 3-3 of Figure 2; A

Figure 4 is a cross section on line 4-4 of Figure 2;

Figure 5 is a plan section on line 5-5 of Figure 2; and

Figure 6 is a fragmentary vertical longitudinal section illustrating amodification in which a second diaphragm as a shield and focusing deviceis employed.

The device comprises two substantially tubular hollow, cylindricalmembers respectively l and 9. In practice the member 1 is of iron,andthe member 9 of cast brass, as a good conductor of heat. The member1, as a support, is flanged at each end as at 2, 3, and

the flange 3 is attached either to the door of a furnace or the pipe maybe elongated and be disposed partially within the furnace or other heatsupplying apparatus. The outer member 9 is flanged as at 4, anda ring 5of spring bronze is interposed between the members. Between this ring 5and flange 4 is inserted a diaphragm ,6, in practice made of springbronze, as a good conductor of heat. This diaphragm, as well as theflangeJ 4, and the ring 5 are made therefore of material havingsubstantiall they same coefficient of expansion. fr[The ame safetydevice as a unit, includingthe casing 9 in which the contact device ismounted, the radiating ring 5 and diaphragmatic element 6, is firstconnected together as follows.

The relatively thin diaphragm 6 is .engaged flatly against the outerside of the stated, the material of the casing, diaphragm and conductingring have the same' or substantially the same coeflicient of expansionand therefore the diaphragm can always be maintained at a highertemperature than the adjacent supporting elements, because radiation andconduction through the casing and ring is more rapid. The

numeral 10 indicates the lirebox door of a furnace, and the numeral 10aindicates a source of flame or heat within the heater or furnace. It isto be understood that the device of this invention is disposed at theouter side of the fire box, so that radiation can take place, tomaintain the element 6 in a condition hereinafter to be described. Itwill be noted that the element 1 is elongated only to that extent whichwill limit the amount of heat delivered to the diaphragm in the desireddegree. The elongation is for the purpose of preventing delivery of toomuch heat. The casing 9 is provided to excludev air, and to providesufficient radiation,

so that the temperature at the inner side of the diaphragm can bemaintained at higher degree than that of the outside. For this purpose,the outer casing not only forms a radiating member but acts to excludeair.

The outer or diaphragm supporting casing 9 is a substantially tubularcasting having the flange 4, is tangentially flattened or constricted asat 11 providing a cross sectionally elongated tubular formation. Thecasting further provides a depression 12 extending in an axial directioninwardly from the flange 4.l A wall 13 divides the member 9 into largeand small chambers, the small chamber 12 being immediately adjacent thediaphragm 6. The wall 13 has an opening 14 therein leading to the largeror outer chamber. Bearing-forming lugs 14TL extend transversely of theconstricted portion from opposite sides and partially thereacross. Thelugs are bored for the reception of trunnion screws 15, the ends ofwhich engage corresponding depressions 14b in opposite sides of the hub15a of the contact control lever or arm 16. This arm 16 is thus pivotedbetween the lugs for oscillation, and

yieldable frictional contact between hub and ribbon may be provided. Bythe use of this ribbon yieldably tensioned and connected to thediaphragm, a slight deflection of the diaphragm will cause a relativelylarge movement of the outer end of the lever, and moreover inasmuch asthe tensioned ribbon exerts a slight deflection-producingaction upon thediaphragm, the same will be caused to deflect in direction of tension ofthe spring, when radiant energy impinges its opposite side. as at 2Oaland engaged against the shoulder is a disc 21 of non-conducting materialhaving an opening 22a. Across this opening projects the arm of aterminal element 23 suitably connected by a screw to the disc and havinga binding screw 25 engaged therewith forsecuring a terminal wire. Thisarm has a terminal extension, upon which is secured by onearm as at 26,a substantially U-shaped contact or circuit-making spring 27. Theopposite unattached arm of this spring has a contact knob or buttonengageable with a similar button carried by a terminal extensionof asecond terminal element 29 secured in a manner similar to element 23,and also having a binding screw. The outer end of the arm 16 is engagedagainst this spring, normally in a manner to keep the contact buttonsfrom engaging to close the circuit. The arm 16 is electrically insulatedas at 16"t and is suitably secured to the hub 15, preferably by beingattached to one face of the same. The contact spring 27 is normally heldcompressed by engagement of the outer end of the arm 16 therewith, and

The casing 9 is shouldered the outer end of said arm is preferablyvslotted providing prongs lying on each side of the button, see Figure 5.As the diaphragm is deflected in direction of the hub, the arm isrotated in clockwise direction to release the upper arm of the springfor making contact.

The outer chamber of the member 9 has a boss 30 threaded to receive apipe in which the electric wires are housed.

The spring 20 is normally under slight tension such as to condition thediaphragm to travel in a direction away from the source of radiantenergy. In this instance, the spring travels upwardly and a depressionof the spring breaks electrical contact. The spring 20 acts to maintainthe frictional contact between the band and the hub of the lever and yetpermits slippage between the two when the travel of the lever is greaterthan is needed, this in order to prevent breakage. Thus it will be seenthat if the movement of the diaphgram in a direction away from thesource of radiant energy is greater than that needed for the upwardmovement of 4the outer end of the lever, slippage will take place andprevent breakage of the lever. The means thus provided is compensatoryin nature and at the same time provides for the positive operatlon of4the contact devices, by the diaphragm.

It will be seen that if heat is applied to the diaphgram 6 at the innerside so as to raise its temperature to a degree greater than that'of theflange and ring, the spring exerting a pull on the ribbon will rotatethe arm as before mentioned. If the diaphragm continues to expand ordeflect after the contact is made, the spring will continue to contractand the ribbon will slip upon the hub. However, when the diaphragm coolsand therefore contracts or straightens, it will exert suflic1ent pull toextend the sprin and by means of fr1ct1onal engagement o the strip withthe hub, the arm will be rotated in counter-clockwise direction and thecontact broken by depression of the spring. If the diaphragm shouldcontinue to contract, the spring would be extended as in the firstinstance, and the arm would continue to travel until stopped by thebracket, and upon continued contraction of the diaphragm, slippagebetween thehub and ribbon will again take place to prevent breakage ofthe arm.

In a device such as herein described, a thin sheet of metal as adiaphragmatic element is used, which heats up rapidly, and it isdesirable to have the diaphragm 6 so constructed and mounted orsupported that the diaphragm will always be at a higher temperature thanthe ring 5 or flange 4. For the purpose of obtaining heat absorption bythe diaphragm the side facing the flame is coated with such a substancethat willincrease the heat absorption, such as carbon paint or lampblack. This substance, because of its thinness, is not shown in thedrawing, but its location is desienated by the numeral 40. The oppositesi e of the diaphragm is left in its natural condition or is burnishedto prevent radiation to assist conduction to the ring and flange. It hasbeen found that when this side is not left in its natural state orbrightened as by polishing, conduction and radiation is, under someconditions, so rapid that the diaphragm cannot be constantly maintainedat the proper degree of deflection to obtain the desired perfection ofoperation.

A section of heat insulating material 3l, in this instance asbestos,although it will be understood that othery non-heat-conductingsubstances may be used such as lava, is interposed between the ring 5and the flange 2, and the ring 5 and flange 4 act as partial conductorsand radiators for heat which is absorbed by the diaphragm 6. The casing9, however, acts as the main conducting and radiating element.

In some instances, it may be found necessary to use a disk 42 ofinsulating material having an opening in the center, the disk beingsubstantially the same diameter as the diaphragm and being placedbetween the insulating ring 43 and the receiving tube. This constructionis illustrated in Figure 6. The opening 45 is of the proper size so thatt-he radiant energy passing therethrough will be localized substantiallyat the center of the diaphragm, so that more efficient use is made ofthe heat, while at the same time, the total amount of heat received bythe diaphragm is materially reduced, thus eliminating the need for greatheat dissipation by the reception tube and thus necessarily maintainingthe housing at a much lower final temperature. In practice, the size ofthe opening and the amount of insulation should be such that the finaltemperature of the housing will not exceed 300 Fahrenheit.

The function of the flame safety unit herein described is to respondpromptly to the presence or absence of flame. In this device the controlelement immediately re` sponds by full deflection, with the oncoming ofthe flame and the deflection immediately decreases with thedisappearance of flame. Inasmuch as the thin diaphragmatic elementabsorbs a large amount of heat, it will expand more rapidly when exposedto the ame. At the same time some of the heat received by thediaphragmatic element must be dissipated or radiated and this isaccomplished by the use of the outer casing 9 and ring 5 as radiatorelements. perature of the diaphragmatic element is always maintained ata higher temperature than that of the flange 4 and ring 5, and,therefore, the temperature at its inner side is always greater than thatat its out-er side. It will further be noted that a relatively largeradiating surface is provided by the flange 4. It will be noted that thedevice responds only to a difference intemperature between the diaphragm6 and its supporting members 4 and 5 and since the suppm'ting membersand diaphragm have the same roeflicient of expansion the temperature ofthe diaphragm can always be maintained at a higher degree than that ofits supporting elements, thus assuring controlling deflection of thesame.

I claim as my invention:

l. A device of the class described comprising a hollow member, aheat-conducting diaphragm attached crosswise of the member and arrangedto be deflected by radiant rays incident thereupon, a radiator memberengaging the diaphragm on the opposite side, the material of saidradiator members and diaphragm having substantially the same coefiicientof expansion, and anelement interposed between the diaphragm and one ofthe radiator members to prevent heat conduction.

2. A device of the class described comprising a tubular member, anasbestos ring engaged against one end of the tube, a diaphragmsubstantially closing the tube, an annular radiator member interposedbetween the diaphragm and asbestos ring, a second radiator member at theopposite side of the diaphragm, means elampingly holding said memberstogether, the material of said radiator members and diaphragm havingsubstantially the same coeiicient of expansion.

3. A device of the class described comprising a hollow member, heatinsulating means disposed terminally of the memberfor reducingconduction, a conducting and radiating ring abutting said heatinsulating means, a diaphragm abutting said conducting ring, and a casmghaving one end abutting said diaphragm' at that side remote from theattaching member, said ring, diaphragm and casing being1 formed ofmaterial having substantially t e same coefficient of expansion.

4. A device of the class described comprising a tubular member, anannular ,insulating element engaging one end of the tube, across-sectionally thick annular radiating member engaging theinsulation, a crossjsectionally thm diaphragmatic element engaging saidradiator member and closing the tubular member, and a second tubularmember engaging the diaphragm at the opposite side and adapted toincrease conduction eifects, said conductin element and diaphragm havingsubstantially the same coefficient of expansion.

5. A device of the class described comprising a hollow member, a heatinsulatin ring disposed terminally against the mem er, a relativelythick annular conducting element abutting said heat insulating member, arelatively thin diaphragm abuttingly engaged against saidy conductingelements, and a second relatively thick annular conducting elementabutting the diaphragm at the opposite side, said conducting elementsand diaphragm having substantially the same coefficient of expansionwhereby radiant energy impinging the diaphragm will be dispersed toconstantly maintain the diaphragm substantially at the same degreeofdeflection, and at a temperature greater than the conducting elements.

6. A device of the class described comprising a hollow member, a heatinsulating ring terminally disposed against the member, and an annularconducting element abutting said heat insulating 'member, a diaphragmabuttingly engaged against said conducting element, a second annularconducting element abutting the diaphragm at the opposite side, saidconducting element and diaphragm having substantially the same coeicientof eX- pansion, whereby radiant energy impinging the diaphragm will bedispersed by the conducting element to constantly maintain the diaphragmat the same degree of deflection andat a temperature greater than seidconducting elements, said diaphragm being blackened upon its receivingside and being polished upon its opposite side.

7 A device of the class described comprising a tubular member, a diaphram closing the member, a ring of heat insu ating material interposedbetween the tubular member and the diaphragm, a casing arranged at theouter side of the diaphra m, in opposition to the lirst mentione member,means securing the members and elements together.

8. A device of the class described comprising a tubular member, adiaphragm closing one end of the member, the periphery of the diaphragmAbeing thickened to increase conduction, a non-heat conducting elementarranged between the diaphragm and the tubular element and a radiatingelement arranged at the outer side of the diaphragm.

9. A device of the class described comprising a support having anopening, a diaphragm closing the opening, an asbestos ring abutting thesupport and diaphragm, to reduce conduction, and a casing arranged atthe opposite side of the diaphra m as a conductor of heat, a switch insai casing and elements connecting the diaphragm and the switch foroperating the same when the diaphra m is deflected and means forproducing l eating effects at that side of the diaphragm opposite thecasing.

10. A support providing a passage, a diaphragm of heat conductingmaterial closing the passage, a device interposed to reduce conductionof heat from the support to the diaphragm, and means at the outer sideof the diaphragm for dissipating heat.

11. A device of the class` described comprising an element as a support,arranged to permit maintenance of a greater temperature inside thanoutside of it, and providing a passage, a metallic diaphragmatic elementclosing the passage, a device for reducing conduction of heat betweenthe support and the diaphragm and an element arranged at the outer sideof the diaphragm for conducting heat therefrom.

12. A device of ,he class described comprising a hollow member, anelement capable of heat absorption and of expansion as the result ofsuch absorption connected to the hollow member in a manner to receiveradiant energy directed to the inside of said member, and meansinterposed between said element and member to reduce heat` conduction. y

13. A device of the class described comprising a hollow member, anelement capable of heat absor tion and of expansion as the result of sucabsorption connected to the hollow member in a manner to receive radiantenergy directed. to the inside lan . my hand this 15th day erally in amanner to increase radiation at the outside of the hollow member.

14. A device of the class described comprising a hollow member, anelement capable of heat absorption and of expansion as the result ofsuch absorption connected to the hollow member in a manner to receiveradiant energy directed to the inside of said member, means interposedbetween said element and member to reduce heat conduction, said hollowmember and element having substantially the same co-ecient of expansion.

15. A device of the class described comprising a hollow member, aheat-sensitive element attached to the member in a manner to bedeflected by radiant energy incident thereupon, and means interposedbetween said heat-sensitive element and said member to reduce heatconduction.

In witness whereof, I have hereunto setof Januar 1926. LEWIS L.CUNNINHAM.

